The invention relates to an apparatus for releasably coupling rotary material removing tools to rotary driving elements, particularly for separably securing grinding wheels or analogous tools to rotary spindles in grinding machines. More particularly, the invention relates to improvements in coupling apparatus of the type wherein the rotary driving element (hereinafter called spindle for short) includes or carries an elongated cone which is receivable in a complementary hole or bore of a flange or hub which is preferably separably connected to and carries the material removing tool. The apparatus of the present invention can be utilized to couple a variety of rotary material removing tools, especially grinding wheels, dressing wheels, profiling rolls and the like.
It is customary to provide the spindle of a grinding machine with an elongated cone which can support and transmit torque to a material removing tool (hereinafter called grinding wheel or tool for short). As a rule, the cone is rather long so as to ensure that its external surface is held in self-locking engagement with the surface surrounding the conical hole or bore of the hub. A drawback of such conventional coupling apparatus is that the axial position of the hub relative to the cone cannot be selected and maintained with a desired degree of accuracy. Furthermore, the self-locking action between the cone and the hub for a grinding wheel or the like exhibits the drawback that the apparatus cannot be actuated by automatic grinding wheel changers.
Attempts to overcome the drawbacks of such conventional apparatus include the utilization of so-called short cones of the type disclosed, for example, in commonly owned German published application No. 34 19 397 and in German Pat. No. 34 03 3661. The utilization of a relatively short cone reduces the likelihood of self-locking and thus simplifies and facilitates the mounting of the hub on as well as separation of the hub from the cone on the spindle. The cone takes up radial stresses, i.e. it serves to center the hub on the spindle. The means for transmitting torque from the spindle to the tool includes end faces at one axial end of the spindle, and such end faces further serve to ensure that the hub is held in a predetermined axial position with reference to the cone. A drawback of coupling apparatus which utilize relatively short cones is that they cannot be used in connection with the mounting of and transmission of torque to relatively large and heavy grinding and like material removing tools.